<!DOCTYPE html>
<html class=reftest-wait>
<title>View transitions: new element is modified while offscren and brought onscreen using pseudo</title>
<link rel="help" href="https://drafts.csswg.org/css-view-transitions-1/">
<link rel="author" href="mailto:khushalsagar@chromium.org">
<link rel="match" href="offscreen-element-modified-before-coming-onscreen-ref.html">

<script src="/common/reftest-wait.js"></script>
<style>
#target {
  width: 100px;
  height: 100px;
  view-transition-name: target;
  position: fixed;
  background: green;
  left: 0;
  top: 200vh;
}

.hidden {
  width: 10px;
  height: 10px;
  background: grey;
  view-transition-name: hidden;
}

.onscreen::view-transition-group(target) {
  transform: unset;
  position: fixed;
  top: 0;
  left: 0;
  animation: unset;
}

html::view-transition-group(hidden) { animation-duration: 300s; }
html::view-transition-image-pair(hidden) { animation: unset; opacity: 0; }

html::view-transition-old(target) { animation: unset; opacity: 0; }
html::view-transition-new(target) { animation: unset; opacity: 1; }

</style>

<div id=target class=target>
<div id=hidden class=hidden></div>

<script>
failIfNot(document.startViewTransition, "Missing document.startViewTransition");

function bringOnscreenAndScreenshot() {
  document.documentElement.classList.add("onscreen");

  requestAnimationFrame(() => requestAnimationFrame(() =>
      requestAnimationFrame(() => requestAnimationFrame(takeScreenshot))
    ));
}

async function runTest() {
  // Start the transition while the element is offscreen.
  let transition = document.startViewTransition();
  await transition.ready;

  // Change the element's color while its still offscreen.
  target.style.background = "blue";

  // Bring the element onscreen and ensure the color change is presented.
  requestAnimationFrame(() => requestAnimationFrame(() =>
    requestAnimationFrame(() => requestAnimationFrame(
      bringOnscreenAndScreenshot))
  ));
}
onload = () => requestAnimationFrame(() => requestAnimationFrame(runTest));
</script>

